In a conventional heat pump hot water supply device, in order to perceive the amount of hot water stored inside a hot water storage tank, a plurality of hot water storing tanks is arranged in series and, among these hot water storing tanks, a bottom portion of the preceding one of two continuously connected hot water storing tanks and an top portion of the following one of the two continuously connected hot water storing tanks are connected to each other, temperature sensors (in this case, six temperature sensors) such as thermistors, which measure internal water temperatures, are each provided in the corresponding one of the hot water storing tanks, and the amount of stored hot water is determined by comparing a temperature from each of the temperature sensors with a set temperature (see Patent Literature 1, for example).